Long Distance Supply at Low Voltage
Long Distance Supply at Low Voltage
(OP)
Is there any practical limit to LV circuit length, and what are the limits?
A small offshore platform will have 24V DC loads that look like they will translate to no greater than about 3 amps per phase at 415V/50Hz. The platform is to be about 12 km from the nearest 415V point of supply.
It appears possible to install a mixture of solar panels, wind turbines and batteries but I wonder if it would be practical to cable in a 415V supply (accepting that reasonably large cross sectional area conductors would be required and that installation would be very expensive).
Any thoughts?
Regards
A small offshore platform will have 24V DC loads that look like they will translate to no greater than about 3 amps per phase at 415V/50Hz. The platform is to be about 12 km from the nearest 415V point of supply.
It appears possible to install a mixture of solar panels, wind turbines and batteries but I wonder if it would be practical to cable in a 415V supply (accepting that reasonably large cross sectional area conductors would be required and that installation would be very expensive).
Any thoughts?
Regards






RE: Long Distance Supply at Low Voltage
RE: Long Distance Supply at Low Voltage
RE: Long Distance Supply at Low Voltage
RE: Long Distance Supply at Low Voltage
Yes, its a very small load. It is very attractive to go solar/wind with lots of batteries. It is just that I am a little wary of such things and it would be good to have the option of "proper" power. I am checking out solar/wind vendors, can you suggest any?
The whole of the platform will be an IEC zone 1 hazardous area (North American class 1 div 1) so whatever is installed will need to be Ex rated equipment. A (fossil fuel?) powered generator is not realy being considered because of reliability concerns (the platform is to be unmanned and very infrequently visited).
An earlier version of the platform would have had more load so supply was to be at 11kV with an on-board Ex rated transformer. Now the load has shrunk so much that solar/wind/batteries may well be viable. It's just that if I wanted to provide proper power, it seems silly to put in 11kV and transformer for such a small load. So, I was wondering if supply at 415V over 12km would be practical (if not laughable)? Is there anything other than voltage drop that would come in to play?
Regards
RE: Long Distance Supply at Low Voltage
RE: Long Distance Supply at Low Voltage
The volt drop is not an issue at all for a 3 amp feeder noting that the transformer at the sending end can also have its taps set down to say -5% to help the situation.
RE: Long Distance Supply at Low Voltage
2) Your load is very small and voltage drop does not seem to be a problem, however length of cable is.
3) I think dont go for short cuts. Calculate appropriate size of cable for this length. Buy submarine cables, suitable jointing kits and take 415 V to that location.
4) Otherwise you need a step up transformer to step up voltage from 415 V to 11 kV. Carry 11 kV to your Offsite. Step down from 11 kV to 415 V.
RE: Long Distance Supply at Low Voltage
http://www.backwoodssolar.com/Catalogpages2/pvmount2.htm#WIRING
for more info.
Maybe, there is a custom-way to make the solar cell panel and associated electrical installations explosion-proof.
RE: Long Distance Supply at Low Voltage
http://www.kellysearch.com/product-7003801.html
solar cell suppliers for explosion proof solar cell panels
RE: Long Distance Supply at Low Voltage
Jbartos, thanks for the references. As it happened I had already contacted one of them and a response is due this week. It will be interesting to see how they comply with the hazardous area requirements.
Regards
RE: Long Distance Supply at Low Voltage